Bug#466546: cryptroot-system fails booting after multipath-tools install

[Guido Günther]

priority: normal
Thanks,
 -- Guido

Hi Chris, 
On Tue, Feb 19, 2008 at 02:42:30PM +0100, debian at x.ray.net wrote:
> symptoms:
> after installation of multipath-tools, booting is not possible anymore.
> the root device isn't multipath but in this case dm-crypt.
> the problem occurs when the cryptroot password prompt should appear - it
> just doesn't but each cryptsetup try outputs a 'Command failed: Can not
> access device' and when the maximum number of tries is exceeded the boot
> process fails because no root-fs can be found.
If you install multipath-tools-boot we assume you want multipath for
your rootfs, otherwise the package shouldn't be installed.

> there's also a multipath device created for /dev/sda5 (with a single path).
> from now on, cryptsetup /dev/sda5 fails ('Can not access device' - but
To protect against havoc - that's perfectly fine.

> calling cryptsetup on the respective multipath device works.
> as this will probably happen in all cases when multipath is installed to
> access a multipath connected device while the root-fs is on a
> non-multipath device, i think this should be solved.
Uninstall multipath-tools-boot, that's why we split it into an extra
package.

> thoughts on solutions:
> i don't really know why /dev/sda5 can't be accessed by cryptsetup
> anymore when multipath is using it, but that's obviously what's  
> happening and i tend to assume that it probably makes some technical  
> sense. on the other hand, if that can be changed, it's probably a very  
It does, see above.

> practical solution.
> another possible solution is, i guess, to implement an option in the  
> multipath binary, to ignore i.e. not create a multipath device for  
> devices which are connected only singlepath. but this will break the  
> boot process in case of a root-fs multipath device in cases of failure  
> of paths so that there's only a single path left.
Exactly.

> maybe it were most straightforward to change the devicenames in  
> /etc/crypttab on installation before mkinitramfs. but following this  
> rationale means the multipath package/installation had to regard each  
> and every devicename configuration in the system...
You can blacklist devices via multipath.conf, that should be fine as an
option, see the manpage.

> or maybe multipath shouldn't be installed to initramfs on (non-initial)  
> installation.
It only get's installed when you install multipath-tools-boot. Maybe I
should clarify the description - would this help?
Cheers,
 -- Guido